Prevalence and zoonotic implications of Dirofilariasis in shelter dogs in Gilan province, Iran

Dirofilariasis, caused by Dirofilaria immitis (D. immitis), is a zoonotic disease. Iran is an endemic country, and shelter dogs are particularly susceptible due to limited veterinary care, high-density housing, and increased exposure to mosquito vectors. This study aimed to determine the prevalence of D. immitis in shelter dogs in Gilan province, northern Iran, using a combined parasitological and molecular approach. A total of ۲۷۱ blood samples were collected from shelter dogs across seven cities in Gilan province. All samples were initially screened for microfilariae using the modified Knott's test. Subsequently, they were analyzed by a species-specific PCR targeting the ۱۵۵ bp partial sequence of the ITS۱ gene of D. immitis, with the beta-actin gene amplified as an internal control. The modified Knott's test identified microfilariae in ۳۲ dogs (۱۱.۸۰% prevalence), while PCR analysis detected D. immitis DNA in ۱۴۳ dogs, corresponding to a significantly higher prevalence of ۵۲.۸%. Measurements taken with Axiovision software (v۴.۱) yielded average microfilarial dimensions of ۳۰۱.۸۹ µm in length (±۱۳.۳۵۱) and ۶.۳۹۲ µm in width (±۰.۵). This discrepancy highlights a substantial number of occult (amicrofilaremic) infections, and the hyper endemic status of D. immitis in shelter dogs in Gilan province. Within the shelter environment, the high-density housing of susceptible dogs creates an amplification hotspot. In Gilan province, the hyperendemicity is likely driven by environmental and entomological factors. These findings necessitate the development of integrated control strategies, including routine molecular screening, preventive chemotherapy, and formal shelter management protocols, to mitigate animal suffering and reduce zoonotic risk.

کلیدواژه ها:

Dirofilaria immitis ITS۱ locus ، Microfilariae ، One health ، Modified Knott’s test